05000336/LER-2019-001, Manual Reactor Trip Due to Loss of the a Steam Generator Feed Pump
| ML20050D676 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/19/2020 |
| From: | Daugherty J Dominion Energy Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 20-003 LER 2019-001-00 | |
| Download: ML20050D676 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(B), System Actuation 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3362019001R00 - NRC Website | |
text
Dominion Energy Nuclear Connecticut, Inc.
Rt 156, Rope Ferry Road, Waterford, CT 06385 DominionEnergy.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2
- LICENSEE EVENT REPORT 2019-001-00 Serial No.: 20-003 MPS Lie/LO RO Docket No.: 50-336 License No.: DPR-65 FEB 1 9 2020 MANUAL REACTOR TRIP DUE TO LOSS OF THE 'A' STEAM GENERATOR FEED PUMP This letter forwards Licensee Event Report (LER) 2019-001-00, documenting an event at Millstone Power Station Unit 2, on December 27, 2019. This LER is being submitted pursuant to 10 CFR 50. 73(a)(2)(iv)(A) as an event that resulted in manual or automatic actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).
Should you have any questions or require additional information, please contact Mr. Jeffry A. Langan at (860) 444-5544.
Sincerely, J:JR.K Site Vice President - Millstone Enclosure: LER 336/2019-001-00 Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.
Suite 100 King of Prussia, PA 19406-2713 R.V. Guzman Serial No.20-003 Docket No. 50-336 Licensee Event Report 2019-001-00 Page 2 of 2 NRC Senior Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C-2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
ATTACHMENT Serial No.20-003 Docket No. 50-336 Licensee Event Report 2019-001-00 LICENSEE EVENT REPORT 2019-001-00 MANUAL REACTOR TRIP DUE TO LOSS OF THE 'A' STEAM GENERATOR FEEDWATER PUMP MILLSTONE POWER STATION UNIT 2 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
NRC FORM 366 (04-2018)
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of' U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
(See NUREG-1022, R.3 for instruction and guidance for completing this form httg://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1. Facility Name Millstone Power Station Unit 2
- 4. Title APPROVED BY 0MB: NO. 3150-0104 EXPIRES:
03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 2. Docket Number
- 3. Page 05000336 1
OF 2 MANUAL REACTOR TRIP DUE TO LOSS OF THE 'A' STEAM GENERATOR FEED PUMP
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year 05000 Docket Number 12 27 2019 2019 -
001
- - 00 02 19 2020 05000
- 9. Operating Mode
)
No Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
On December 27, 2019 at 0704 while operating in MODE 1 at 100 percent power, operators manually tripped the Millstone Power Station Unit 2 (MPS2) reactor due to lowering steam generator levels caused by a loss of flow from the 'A' Steam Generator Feed Pump (SGFP).
The direct cause was the failure of the coupling connecting the MPS2 'A' Steam Generator Feed Pump (M2P1A) to the Steam Generator Feed Pump Turbine (M2H-5A).
The failed 'A' SGFP coupling was replaced and MPS2 was returned to service.
The actuation of Reactor Protection System (RPS) and Auxiliary Feedwater System (AFW) is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in a manual or automatic actuation of systems listed in 10 CFR
- 50. 73(a)(2)(iv)(B).
1.
EVENT DESCRIPTION
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 2. DOCKET YEAR 05000336 2019
- 3. LER NUMBER SEQUENTIAL NUMBER 001 REV NO.
00 On December 27, 2019 at 0704 while operating in MODE 1 at 100 percent power, operators manually tripped the Millstone Power Station Unit 2 (MPS2) reactor due to lowering steam generator levels caused by a trip of the 'A' Steam Generator Feed Pump (SGFP). All control rods inserted on the reactor trip. The reactor trip was uncomplicated and heat removal was via the steam dumps to the condenser. All safety systems functioned as required.
Following the reactor trip, main feedwater continued to be available. Steam generator level was restored to the post trip band using main feedwater. An actuation of the Auxiliary Feedwater System occurred following the manual reactor trip as designed, as a result of low level in the steam generators.
The actuation of Reactor Protection System (RPS) and Auxiliary Feedwater System (AFW) is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in a manual or automatic actuation of sytems listed in 10 CFR 50.73(a)(2)(iv)(B).
2 CAUSE
The direct cause was the failure of the coupling connecting the MPS2 'A' Steam Generator Feed Pump (M2P1A) to the Steam Generator Feed Pump Turbine (M2H-5A). This resulted in loss of motive force to the 'A' SGFP, a Steam Generator Feed Pump Turbine overspeed trip, subsequent lowering of the steam generator level and a manual reactor trip.
3.
ASSESSMENT OF SAFETY CONSEQUENCES
There were no safety consequences related to this event. The operations crew responded to the loss of the SGFP by initiating a manual reactor trip. All control rods inserted on the reactor trip and all emergency systems functioned as designed. The steam generator safety valves did not lift. Main feedwater continued to be available post reactor trip as expected. Condenser vacuum was maintained following the trip allowing heat removal via the steam dumps to the condenser. Because of the loss of the 'A' SGFP, steam generator level dropped below the Auxiliary Feedwater (AFW) actuation setpoint, and AFW was delivered to both steam generators until the operators secured AFW approximately 9 minutes after AFW actuation. All reactor coolant pumps continued to operate and the Reactor Coolant System (RCS) temperature was maintained within the normal post trip band of 530 - 535 degrees fahrenheit following the event.
Following reactor trip, the minimum pressurizer pressure was approximately 1941 psia, which is within the normal post trip operating band. As expected, a backup charging pump started, and letdown was minimized due to a deviation from the programmed pressurizer level setpoint. The control system restored pressurizer level to its programmed level as designed. All safety systems operated as required. Therefore, no safety functions were challenged, and plant operation was maintained within the bounds of the FSAR chapter 14 safety analysis.
4.
CORRECTIVE ACTION
The failed 'A' SGFP coupling was replaced and MPS2 was returned to service. The 'B' SGFP coupling was inspected and determined to be satisfactory. Additional corrective actions are being taken in accordance with the station's corrective action program.
5.
PREVIOUS OCCURRENCES
There have been no manual reactor trips at MPS2 with an apparent cause linked to a SGFP failure in the past 3 years.
6.
Energy Industry Identification System (EIIS) codes BA-Aux Feedwater/ Emergency Feedwater system SJ - Feedwater System CPLG - CouplingPage 2 of 2